16555 - Fuel Trim; Bank 1: System Too Lean

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my engine managment light came on with the folowing fault 16555 - Fuel Trim; Bank 1: System Too Lean i checked measuring blocks 32 and 33 with my vag com, on 32 everything looks good but on 33 it is out of limits goes up to 21% and the limit is 10% any ideas what is wrong with my car?

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too lean could be a VAC leak. IE unmetered air being drawn into the engine. AS your engine is non turbo you need to check all the inlet pipes after the MAF for signs of leak. if you spray carb cleaneraround the inlet pipes with the engine at idle you will hear the engine note pickup when you spray near a leak. (only needs a small amount though, don't go soaking the pipes as it should be easily noticed) HTH

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Try clamping off the breather pipe where it goes into the inlet pipe and see if it alters. Depends on which 1..6 it is but I have seen the valve on the breather system fail and it sucks to much into the inlet so the ECU leans off the mixture.

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